Yes - just affix a long enough string to the end of the hydrometer - make sure you sanitize the string before use! A better approach would be to use a turkey baster, and better still - a wine thief.
I think anything you attach to it will change the weight and throw off your reading. Much better to take a sample out of the fermenter, test it and then drink it!
Oh, and a hygrometer won't do much for brewing. You probably want to use a hydrometer instead.